Various ways of coupling two rotational shafts and/or hubs together are known in the art. Often times, the couplings are used to transmit torque or rotational power from a drive shaft or hub to a driven drive shaft or hub. Thus, typically on one side of the coupling there is a power inducing device such as a motor, and on the other side of the coupling there is a shaft input to a power receiving device.
One example of such an arrangement is in a drive system for a fan used in an atmospheric cooling tower. In such a situation, it is common for the fan to be a relatively large horizontal or vertical axial fan. Often times, the blades are mounted to a hub and gear box in the center of the fan assembly, which is the axis about which the fan rotates. The gear box is often a 90 degree gear box, such that the axis of the input shaft to the gear box is at a right angle compared to the center line axis of the fan. Typically, a power transmission shaft extends from the center gear box along and past the radial swept area length of the fan, to a motor which is radially disposed outside the periphery of the fan. In this way, the motor is outside the swept area of the fan and does not block the air flow through the fan. Further, the gear box can be made relatively compact and rests in the center of the fan underneath the fan center hub.
The systems described above have proven highly satisfactory in use. However, particularly due to the length of the power transmission drive shaft, and to the construction of cooling towers in general, it has often been difficult to maintain a precise alignment between (1) the output shaft center axis of the motor, (2) the shaft center axis, and (3) the input shaft center axis of the gear box. Any misalignment is exacerbated by the relatively long length of the transmission shaft.
One solution to this issue has been to provide some form of torque tube or other rigid device spanning between the motor and the gear box. However, torque tubes do not always provide or maintain satisfactory alignment by themselves.
Accordingly, there is a need in the art for an improved connection or coupling which can be interposed at one or both ends of a shaft or hub, such as a driven shaft between a motor and a gear box, in order to accommodate misalignment that may occur.